This invention relates to a method for the manufacture of a double-row blade wheel for a fluid-flow machine and to a double-row blade wheel.
It is known to use double-row blade wheels, also referred to as tandem blade wheels, in a fluid-flow machine. A fluid-flow machine with a double-row stator wheel is known from EP 2 261 463 A2, said wheel including two directly adjacent, stationary stator vane rows. A double-row blade wheel is for example also known from U.S. Pat. No. 6,009,249 A.
With a double-row blade wheel, it must be ensured that the offset in the circumferential direction between the blades of the two grid rows of the double-row blade wheel is exactly set. In a stator wheel, this offset in the circumferential direction, and the act of providing it, is also referred to as circumferential positioning or “clocking”.
Compared with blade wheels with only one grid row, a double-row blade wheel thus requires a considerable construction effort, since the two grid rows have to be positioned very precisely relative to one another to achieve an aerodynamic advantage over a single-row design of the blade wheels. This leads to double-row blade wheels only being used for specific aerodynamic tasks and not being widespread so far.